Genomic DNA is extracted from whole blood. The RAF1 gene is amplified by polymerase chain reaction (PCR). The PCR product is then purified and sequenced in both directions using fluorescent dye-terminator chemistry. Sequencing products are separated on an automated sequencer and trace files analyzed for variations in the exons and intron/exon boundaries of all 17 exons using mutation detection software and visual inspection.(Unpublished Mayo method)